The present invention relates to implantable lead systems used with an implantable cochlear stimulator, and more particularly to an insertion tool used to insert an implantable lead system into a human cochlea.
Cochlear electrodes are generally built in the form of elongated, flexible polymer structures with array contacts and connecting wires. It is generally understood that the best performance from a cochlear implant is achieved with the electrode contacts on the cochlear electrode are facing and closely positioned to the modiolar wall of the cochlea.
There are two main types of electrode systems designed to place the electrode contacts in perimodiolar (near or around the modiolus) position. The first is as described in U.S. Pat. No. 6,038,484 or 6,195,586, both of which patents are incorporated herein by reference; and the second is as described in U.S. Pat. No. 6,125,302; also incorporated herein by reference.
To reduce damage to the cochlea structure, electrode carriers are made from very soft, flexible material, and because of this characteristic, they are generally difficult to insert into the cochlea without the use of special supporting tools. An example of such insertion tools is described in U.S. Pat. Nos. 5,443,493 and 6,149,657, both of which patents are also incorporated herein by reference.
The insertion tools described in the referenced patents are designed for use with a particular type of electrode system. Such tools thus do not function adequately with other types of electrode systems. There is thus a need in the art for a more universal insertion tool for use with more than one type of electrode/positioner system.
One type of electrode/positioner system commonly used, referred to herein as the “HiFocus II” electrode, is the type described in U.S. Pat. No. 6,195,586, or electrode/positioner systems similar thereto, wherein a distal tip of the flexible positioner is attached near, but not at, the distal tip of the electrode carrier.
Another type of electrode/positioner system also commonly used, referred to herein as the “HiFocus” electrode, is the type described in U.S. Pat. No. 6,038,484, wherein a flexible positioner and the electrode array, as separate detached elements, are inserted into the cochlea. A preferred electrode array and positioner for use with such a HiFocus electrode are disclosed in U.S. Pat. No. 6,129,753 (electrode array) and U.S. Pat. No. 6,078,841 (positioner), both of which patents are incorporated herein by reference.
Yet another type of electrode system commonly used, referred to herein as the “Highly Pre-curved Electrode”, is disclosed in U.S. Pat. No. 6,125,302.